Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects

Platinum-modified-βNiAl is a bond coat (BC) material for thermal barrier coatings (TBCs) applications applied on aeroengine hardware to reduce their surface temperatures. However, it is desirable to minimize its production and material costs by the low-cost alternatives of similar performance. It ha...

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Autores principales:	Chandio A.D., Shaikh A.A., Salman W., Ahmed H.
Formato:	article
Lenguaje:	EN
Publicado:	Technical Faculty, Bor 2021
Materias:	βnial bond coat oxidation resistance thermal barrier coating (tbc) doping of reactive metals (res) aluminizing Mining engineering. Metallurgy TN1-997
Acceso en línea:	https://doaj.org/article/f66435370f884682ad5e41839f63308b
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spelling	oai:doaj.org-article:f66435370f884682ad5e41839f63308b2021-11-22T11:04:01ZProcessing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects1450-53392217-717510.2298/JMMB201108026Chttps://doaj.org/article/f66435370f884682ad5e41839f63308b2021-01-01T00:00:00Zhttp://www.doiserbia.nb.rs/img/doi/1450-5339/2021/1450-53392100026C.pdfhttps://doaj.org/toc/1450-5339https://doaj.org/toc/2217-7175Platinum-modified-βNiAl is a bond coat (BC) material for thermal barrier coatings (TBCs) applications applied on aeroengine hardware to reduce their surface temperatures. However, it is desirable to minimize its production and material costs by the low-cost alternatives of similar performance. It has been acknowledged that the small concentration of the reactive elements (REs), such as Zr, Hf, and Y, could tremendously enhance the oxide adhesion even in some cases better than Pt modified counterparts. The aim of this study was to design and fabricate the Zr-modified-βNiAl bond coat on CMSX-4 superalloy using an aluminizing method. Moreover, the study focused on the development of a systematic understanding of underlying mechanisms behind the beneficial effects of REs. Initially, three sets of BCs were prepared: Zr-free βNiAl (undoped), Al and Zr co-deposited in a single-step process (1SP), and Zr and Al, which were individually deposited in two processing steps (2SP): zirconizing and aluminizing. Such three sets of BCs helped to understand the processing, as well as Zr and Al effects on scale adhesion. In particular, 1SP/2SP BCs showed uniformity of Zr in the form of precipitates and networks that caused hardness enhancement. All BCs were isothermally oxidized at 1150°C for 100 hours wherein 2SP revealed the best spallation resistance, microstructural stability, and its Zr-oxide pegs were extended to substrates. In addition to the Zr effect, BC Al content was found to affect the oxide adhesion equally. Under identical Zr contents (of 1SP and 2SP = 1at %), the higher Al showed the better spallation resistance while lower Al caused the inverse effect of Zr owing to its reactive nature that was termed as over doping. Moreover, it was established that over-doping either local or into entire BC, accelerated the Al depletion that destabilized the βNiAl into γ’-Ni3Al phase. An extensive discussion is presented in the light of the observed results.Chandio A.D.Shaikh A.A.Salman W.Ahmed H.Technical Faculty, Borarticleβnial bond coatoxidation resistancethermal barrier coating (tbc)doping of reactive metals (res)aluminizingMining engineering. MetallurgyTN1-997ENJournal of Mining and Metallurgy. Section B: Metallurgy, Vol 57, Iss 3, Pp 301-308 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	βnial bond coat oxidation resistance thermal barrier coating (tbc) doping of reactive metals (res) aluminizing Mining engineering. Metallurgy TN1-997
spellingShingle	βnial bond coat oxidation resistance thermal barrier coating (tbc) doping of reactive metals (res) aluminizing Mining engineering. Metallurgy TN1-997 Chandio A.D. Shaikh A.A. Salman W. Ahmed H. Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects
description	Platinum-modified-βNiAl is a bond coat (BC) material for thermal barrier coatings (TBCs) applications applied on aeroengine hardware to reduce their surface temperatures. However, it is desirable to minimize its production and material costs by the low-cost alternatives of similar performance. It has been acknowledged that the small concentration of the reactive elements (REs), such as Zr, Hf, and Y, could tremendously enhance the oxide adhesion even in some cases better than Pt modified counterparts. The aim of this study was to design and fabricate the Zr-modified-βNiAl bond coat on CMSX-4 superalloy using an aluminizing method. Moreover, the study focused on the development of a systematic understanding of underlying mechanisms behind the beneficial effects of REs. Initially, three sets of BCs were prepared: Zr-free βNiAl (undoped), Al and Zr co-deposited in a single-step process (1SP), and Zr and Al, which were individually deposited in two processing steps (2SP): zirconizing and aluminizing. Such three sets of BCs helped to understand the processing, as well as Zr and Al effects on scale adhesion. In particular, 1SP/2SP BCs showed uniformity of Zr in the form of precipitates and networks that caused hardness enhancement. All BCs were isothermally oxidized at 1150°C for 100 hours wherein 2SP revealed the best spallation resistance, microstructural stability, and its Zr-oxide pegs were extended to substrates. In addition to the Zr effect, BC Al content was found to affect the oxide adhesion equally. Under identical Zr contents (of 1SP and 2SP = 1at %), the higher Al showed the better spallation resistance while lower Al caused the inverse effect of Zr owing to its reactive nature that was termed as over doping. Moreover, it was established that over-doping either local or into entire BC, accelerated the Al depletion that destabilized the βNiAl into γ’-Ni3Al phase. An extensive discussion is presented in the light of the observed results.
format	article
author	Chandio A.D. Shaikh A.A. Salman W. Ahmed H.
author_facet	Chandio A.D. Shaikh A.A. Salman W. Ahmed H.
author_sort	Chandio A.D.
title	Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects
title_short	Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects
title_full	Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects
title_fullStr	Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects
title_full_unstemmed	Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects
title_sort	processing, characterisation and oxidation resistance of βnial bond coat: al and zr effects
publisher	Technical Faculty, Bor
publishDate	2021
url	https://doaj.org/article/f66435370f884682ad5e41839f63308b
work_keys_str_mv	AT chandioad processingcharacterisationandoxidationresistanceofbnialbondcoatalandzreffects AT shaikhaa processingcharacterisationandoxidationresistanceofbnialbondcoatalandzreffects AT salmanw processingcharacterisationandoxidationresistanceofbnialbondcoatalandzreffects AT ahmedh processingcharacterisationandoxidationresistanceofbnialbondcoatalandzreffects
_version_	1718417771514036224

Processing, characterisation and oxidation resistance of βNiAl bond coat: Al and Zr effects

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